His event Thursday morning will mark his 153rd fundraiser since announcing his reelection bid last year. That’s nearly double the number that his predecessor George W. Bush had attended by this point in his reelection campaign, according to CBS’s Mark Knoller, who put 43’s early June number at 79.

Republicans have pounced on the increasing amount of time Obama has spent on fundraising, calling him “the campaigner-in-chief.” But Obama’s harried pace can also be viewed as just another example of what a big deal money has become in American elections, particularly since outside groups with unlimited contributions have dramatically upped the ante.

Obama campaign officials suggested that was the case.

"The Citizens United decision opened the floodgates for special interests to give unlimited amounts of money from secret donors in an attempt to defeat the president," campaign spokeswoman Katie Hogan said in a statement. "Therefore this campaign must and will continue to fight hard against the millions of dollars of negative advertising supported by Mitt Romney and his undisclosed special interest allies."

Obama, like all federal candidates, is basically limited to taking in $35,800 per donor -- $5,000 for a campaign committee and $30,800 for the national party. But since Citizens United in 2010, outside groups - that are not subject to the limits -- have been allowed to spend unlimited amounts on political campaigns.

Despite his spending so much time fundraising, Obama and the groups supporting him are not taking in as much as Romney and the groups supporting him, according to a recent tally by POLITICO’s Ken Vogel. Romney and his backers, including super PACs, had raised a total of $402 million by the end of April, compared to $340 million raised by Obama and his backers.